The present invention relates to message illumination assemblies and, more particularly, to ones having light enclosures with individual light chambers which can be manufactured and assembled from a single piece of plastic.
Instrument clusters are utilized in automobiles and the like to provide information to the driver or operator. Instrument clusters typically include one or more message illumination by a light source upon the illumination assembly includes a grouping of indicator messages which are illuminated by a light source upon the occurrence of a predetermined condition. In automobiles, for example, message illumination assemblies may provide indicator messages for low oil pressure, high temperature, non-fastened seat belts, engaged parking brake, etc. When one of these conditions occurs, a light source corresponding to the proper indicator message will be activated, thereby illuminating the indicator message to inform the driver of the condition.
Generally, message illumination assemblies are provided with means to direct as much of the light from the light source as possible through the indicator message. In this manner, the driver will not be confused as to which indicator message is illuminated, and the illumination requirements of the light source will be minimized. Such means for directing the light through the indicator message typically include a light enclosure which is formed behind the indicator messages. Partitions are included within the light enclosure to provide a separate light chamber behind each indicator message. A separater light source is placed inside of each light chamber. Two openings are provided in each chamber--one for entry of the light source, and one through which light passes to the indicator message.
In the past, such message illumination assemblies have been constructed from two or more separate molded plastic pieces. After being molded, the pieces are assembled and affixed to one another to form the light enclosure of the message illumination assembly. An example of a message illumination assembly/light enclosure formed in this manner is disclosed in U.S. Pat. No. 4,177,497 to McCook et al. Such message illumination assemblies are disadvantageous, however, particularly in terms of their manufacture.
The manufacture of conventional message illumination assemblies necessitates the molding and assembly of two or more individual plastic pieces to form the light enclosure portion. If the light source and indicator message openings are located on adjacent surfaces, the light enclosure portion requires at least one of the plastic pieces to be made from a complicated three piece slide mold or yet another additional piece of plastic.
Such manufacturing requirements are disadvantageous for a number of reasons. At least twice the mold components, molding steps, and costs are encountered as compared to the manufacture of a single plastic piece. If three piece slide molding is used for some of the multiple plastic pieces, expensive mold tooling costs, more frequent maintenance, and increased molding cycle time result. In addition, the variances which occur due to the enclosure's multiple plastic parts (such as warpage, shrinkage, final assembly, etc.) must be tightly maintained to prevent light leakage between individual chambers of the completed assembly. On the other hand, the variances that could contribute to leakage in a single piece of plastic light enclosure would be almost completely eliminated.
Accordingly, it is seen that a need exists in the art for a message illumination assembly having a light enclosure which can be formed in a simple, two-segment mold without the necessity of utilizing a mold slide, and which can be formed from a single piece of molded plastic to virtually eliminate multi-part mating variances and resultant light leakage.